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Difficulty: HardElectricity and Magnetism

Match each electromagnetic device or physical phenomenon on the left with its corresponding fundamental mechanism and energy interaction on the right.

  • Electromagnetic induction in an electric generatorGeneration of an electromotive force (induced voltage) by varying the magnetic flux passing through a closed conductive circuit
  • Magnetic torque production in a direct-current motorGeneration of mechanical rotational force via the magnetic Lorentz force acting on current-carrying conductors inside an external field
  • Joule heating across an electrical resistorConversion of electrical energy into thermal dissipation via collisions between moving charge carriers and conductor atoms
  • Electrostatic energy storage in a capacitorRetention of potential energy in an electric field created by separated opposite charges across an insulating dielectric

Answer

Electromagnetic induction matches the generation of an electromotive force via varying magnetic flux; magnetic torque in a motor matches the Lorentz force acting on current-carrying conductors; Joule heating matches the conversion of electrical energy into thermal dissipation through lattice collisions; and capacitor storage matches the retention of potential energy in an electric field across an insulating dielectric.
Each electromagnetic concept correctly corresponds to its underlying physical law: electromagnetic induction generates voltage from changing magnetic flux, motor action generates mechanical torque from magnetic forces on current, resistive heating results from microscopic electron collisions yielding thermal dissipation, and capacitors store potential energy in the electric field between separated charges.

Step-by-Step Solution

1
Analyze the operational principle of generators versus motors.
Generators convert mechanical work to electricity via changing magnetic flux (induction), whereas motors convert electrical current in a magnetic field to mechanical torque (Lorentz force).
Differentiating between motor action (electrical-to-mechanical) and generator action (mechanical-to-electrical) prevents confusing input and output energy forms.
2
Analyze energy dissipation in resistive components.
Resistive conduction dissipates energy thermally as moving charge carriers collide with conductor ions.
Ohmic resistance transforms electric potential energy irreversibly into internal thermal energy.
3
Analyze static field storage in reactive capacitive components.
Capacitors hold charge statically across a dielectric boundary, storing energy within an electric field rather than dissipating it or relying on continuous charge flow.
Capacitive storage is electrostatic and reversible, contrasting with resistive thermal dissipation and magnetic induction.

Key Concept

Fundamental principles of electromagnetism, circuit components, and electromechanical energy conversions
Estimated Time:1m 30s
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Topics

Electricity and Magnetism

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